Residual Feed Intake, Digestibility of Nutrients and Efficiency of Water Utilizations in Murrah Buffalo Heifers

Abstract

A metabolism trial was conducted for 7d to determine residual feed intake (RFI=measure of the difference between actual feed intake and expected feed requirement), dry matter intake (DMI), digestibility and metabolism of nutrients at the end of a 57 days (d) of a feeding trial with 18 Murrah buffalo heifers (279kg±16; and 684±131d of age). Preliminary selection of heifers as efficient and less efficient was done by regressing actual DMI on predicted DMI (g/head/d) using the model DMI (g/kg BW) = β 0 + β predicted DMI (g/kg BW) and RFI categories were sorted out by regressing mean DMI for the 57 days feeding period on BWG and mid-test MBW using the model Yi = β0 + β1 BWG (g/d) + β2 mid-test MBW (kg) + ei; where Yi = DMI, β0 = regression intercept, β1 and β2 = regression coefficients on BWG and mid-test MBW, respectively, and ei = uncontrolled error or RFI, heifers with +ve RFI values are less efficient and those with -ve RFI values efficient. Differences were not statistically significant. The actual dry matter (DM), crude protein (CP), digestible organic matter (DOM) and total digestible nutrient (TDN) intakes of RFI-I heifers (6.73±0.56; 0.99±0.008; 5.06±0.47; and 4.95±0.47 kg/head/d, respectively) were not different from those of RFI-II (6.51±0.50; 0.97±0.07; 5.11±0.42; and 5.00±0.42 kg/head/d, respectively). RFI-II heifers digested DM, OM and NDF (70.84±1.48; 73.96±1.54 and 66.33±2.08%, respectively) better than those of RFI-I heifers (68.74±1.66; 71.49±1.72% and 63.05±2.32%, respectively) and thus RFI-II had higher N balance (45±8 head/d) than that of RFI-I heifers (38±9 g/head/d). Water loss per unit of water intake (WI) in feces of RFI-II (69.70±8.40 %) was lower than that of RFI-I heifers (73.41 ± 9.39%) and improved amount of water available for RFI-II for metabolism as a result of which water loss in urine proportionally increased in RFI-II (32.65 ± 2.04%WI) than in RFI-I heifers (31.84 ± 2.28%WI). Water loss per unit of DMI in feces (157 ± 18 vs. 145 ± 16 % DMI) and urine (69 ± 10 vs. 76 ± 9 %DMI, for RFI-I vs. RFI-II, respectively) followed similar trend as that of water loss per unit of WI. Mainly because of small sample size differences in nutrient intakes between RFI-I and RFI-II heifers were not significant; however, RFI-II with similar feed intake had higher N-balance, digestibility of nutrients and level of water utilization and could be selected as being more feed efficient heifers.

Ruminal microbiota is associated with feed-efficiency phenotype of fattening bulls fed high-concentrate diets

“…These results are in accordance with previous studies in which more efficient animals showed a higher nutrient digestibility and a smaller nutrient loss through waste and methane emission (Richardson et al 1996;Nkrumah et al 2006). Negesse et al (2017) also observed improved apparent digestibility coefficients of DM, OM and CP in HE heifers; these animals excreted a smaller proportion of N through faeces and their N biological value (digestible N ratio) was higher than that of less efficient heifers, suggesting that CP digestion and metabolism may be enhanced in HE animals. In comparison, de Assis Lage et al (2019) did not find differences in digestibility coefficients of such nutrients but they reported a tendency of HE heifers to better digest ether extract fraction.…”